The present invention relates to an apparatus and method for releasably locking an transducer actuator assembly at a fixed position relative to a disk. More particularly, the present invention relates to an improved apparatus and method for releasably locking an actuator assembly.
The assignee of the present invention has pioneered the concept of an aerodynamically released actuator latch for hard disk drive. By way of example, the reader""s attention is directed to commonly assigned U.S. Pat. No. 4,538,193 for xe2x80x9cAerodynamically Released Safety Latch for Data Transducer Assembly in Rotating Rigid Disk Data Storage Devicexe2x80x9d. The disclosure of the referenced patent is incorporated herein by reference. The reader""s attention is further directed to U.S. Pat. No. 5,319,511 for xe2x80x9cAerodynamic Actuator Latch with Magnetic Return Spring for Hard Disk Drivexe2x80x9d and U.S. Pat. No. 5,717,544 for xe2x80x9cPressure Differential Latch for a Disk Drivexe2x80x9d. The disclosures of the referenced patents are also incorporated herein by reference.
Aerodynamically released shipping latches of the type described in the referenced patents have proven very successful in operation. The distinct advantages of an aerodynamically released shipping latch and its manner of operation are explained in these prior patents. Several drawbacks of aerodynamically released shipping latches in accordance with the inventions described in the cited patents have remained unsolved until the present invention. One drawback is associated with the type of latch shown in FIG. 1a. As shown, an air vane portion of this type of latch extends above, below and/or in between the disks when the latch is engaged with the actuator assembly 12, which is parked in a landing zone 14 when the disks 15 are not rotating. In the magnified view of FIG. 1b, it can be seen that a latching arm 32 engages a latching extention 12a of actuator assembly 12, thereby preventing the actuator from rotating away from the landing zone 14. Referring to FIGS. 2a and 2b, as the disk drive powers on and the disks 15 rotate, a resultant airflow impinges upon the air vane portion 11, forcing the latch 16 to rotate in a clockwise direction to disengage from the actuator assembly 12 as the actuator assembly 12 also rotates in a clockwise direction away from the landing zone 14 and onto the data zone 17. Accordingly, this type of shipping latch is susceptible to disengagement by a rotary shock that causes the latch and actuator to rotate in the clockwise direction, resulting in possible damage to the disk surface, transducer head and data zone. Another drawback of this design is that the air vane portion, which extends into the airflow generated by the rotating disk, causes aerodynamic drag, which increases the power consumption of the drive. Since aerodynamic drag is proportional to the square of velocity, this is a particular concern for high speed drives e.g. 10,000 rpm.
Another drawback is associated with the type of latch shown in FIG. 3a, which shows the latch 86 in a latched position. As shown, this type of latch is positioned xe2x80x9cdownstreamxe2x80x9d of the actuator assembly 12. The forces that operate this type of latch is created as the actuator assembly partially blocks a portion of the airflow generated by the disk rotation. This creates a difference in air pressure between the regions 80 and 85 as shown in FIG. 3a. As the disk 15 rotates, the pressure difference integrated over the air vane portion 87 overcomes a bias mechanism (not shown) to rotate the latch in the direction, indicated by arrow C, disengaging itself from the actuator, as illustrated in FIG. 3b. This type of latch occupies space that may also be needed to route a flex circuit. Because of the lack of overall space within a disk drive, and the lack of alternative positions to locate the flex circuit, positioning a latching mechanism downstream from the actuator assembly makes routing the flex circuit cumbersome and time consuming. Another drawback of this type of latch is that it requires an arm attached to the actuator, which increases inertia and cost and is susceptible to vibration.
Thus, there exists a need for an improved, simple and cost efficient latching mechanism which can effectively use the airflow generated by a spinning disk, which does not require increased power use and is not susceptible to rotary shock.
The latching mechanism of the present invention satisfies these needs.
A general object of the present invention is to provide a latching mechanism for a transducer actuator assembly of a disk drive assembly which overcomes the limitations and drawbacks of the prior art latching devices.
A more specific object of the present invention is to provide a latching mechanism utilizing a single rigid air vane positioned in close proximity to the rotating data storage disks, which is deflected to rotate in a counter clockwise direction and to release a transducer actuator assembly by diverted airflow within a disk drive assembly. In an open position, the latching mechanism blocks airflow generated by the spinning disk, thereby creating an area of static high pressure. This static high pressure maintains the latching mechanism in the unlocked position until the disk stops spinning.